The invention lies in the field of connecting optical conductors to optoelectronic components and is to be applied in configuring the design of a configuration wherein an optical conductor is optically coupled to two optoelectronic components, arranged on parallel surface regions of a common substrate, by interposition of a layer acting in a beam splitting fashion. Such coupling configurations are required in order to be able, via a single optical conductor, to transmit either two transmission or reception signals of different wavelengths in a unidirectional fashion, or one transmission and one reception signal in a bidirectional fashion.
The term optoelectronic component as used in the context of this description and the claims is to be understood as a transmitter or a receiver. Under electric control, an optoelectronic component constructed as a transmitter converts electrical signals into optical signals that are emitted in the form of light signals. An optoelectronic component constructed as a receiver converts optical signals that have been applied to it into corresponding electrical signals that can be tapped at the output side. Furthermore, an optical conductor is understood as any device for relaying optical signals guided in a spatially bounded fashion, in particular assembled optical waveguides. A layer acting in a beam splitting fashion is to be understood as all layer structures that serve the geometrical or physical splitting of beams, in particular metal or dielectric reflecting surfaces.
In a prior art optical coupling configuration that is constructed as a bidirectional transceiver module, the light exit surface of one optoelectronic component, constructed as transmitter (laser diode) runs perpendicular to the substrate, while the light entry surface of the other optoelectronic component, constructed as receiver (photodiode) is aligned at an angle of approximately 55xc2x0 to the substrate. That angle results from the fact that the photodiode is constructed in a surface region of a crystal member wherein two crystal planes enclose an angle of approximately 55xc2x0. A layer acting in a beam splitting fashion is constructed on the photodiode. A light bundle emitted by the laser diode is partially reflected at the layer acting in a beam splitting fashion. After deflection by a lens, the reflected light bundle runs perpendicular to the substrate and is launched into an optical conductor. Another light bundle, which runs in a fashion emanating from the optical conductor and perpendicular to the substrate, is reflected by the lens such that, after partial transmission through the layer acting in a beam splitting fashion, it strikes the light entry surface of the photodiode at an angle of incidence of approximately 35xc2x0. It is thereby impossible to use this optical coupling configuration as a unidirectional transmission module by exchanging the receiver (photodiode) for a transmitter. See German published patent application DE 44 11 380 A1.
International PCT publication WO 00 00861 A discloses a generic optical coupling configuration with two optoelectronic components that are arranged next to one another on a common substrate. In this case, the light entry or light exit surface of the first optoelectronic component runs perpendicular to the substrate, and the light entry or exit surface of the second optoelectronic component runs parallel to the substrate. An optical element has a layer acting in a beam splitting fashion that is aligned above the second optoelectronic component at an angle of approximately 45xc2x0 to the substrate.
U.S. Pat. No. 5,479,540 describes a bidirectional optoelectronic transceiver module in the case of which two optoelectronic components are likewise arranged next to one another on a common substrate. A diffractive disk that is aligned parallel to the substrate serves as a beam splitting layer.
It is accordingly an object of the invention to provide an optical coupling configuration wherein the two optoelectronic components can be constructed both as receivers and as transmitters and which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which is distinguished by a compact design and is easy to adjust.
With the foregoing and other objects in view there is provided, in accordance with the invention, an optical coupling configuration for connecting an optical conductor to first and second optoelectronic components each having a light entry or light exit surface, comprising:
a common substrate having parallel surface regions respectively carrying the optoelectronic components adjacent one another;
wherein the optoelectronic components are arranged such that the light entry or light exit surface of the first optoelectronic component extends substantially perpendicular to the substrate and the light entry or light exit surface of the second optoelectronic component extends substantially parallel to the substrate;
a molded part formed of an optically transparent material and having a first surface fastened on one of the light entry or light exit surfaces and a second surface; and
a beam-splitting layer formed on the second surface above the second optoelectronic component and enclosing an angle of substantially 45xc2x0 with the substrate.
Instead of the molded part, it is also possible, in accordance with a second embodiment of the invention, for the beam-splitting layer to be formed on the coupling end face of the optical conductor.
In other words, in a first variant of the invention it is provided that the layer acting in a beam splitting fashion is constructed on a surface of a molded part that consists of an optically transparent material and which has at least one further surface with the aid of which it is fastened on one of the light entry or light exit surfaces. This permits the optical coupling configuration to be adjusted easily. The molded part can be a prism or a beam splitting cube, for example.
In the second variant of the invention, the layer acting in a beam splitting fashion is constructed on the coupling end face of an optical conductor running parallel to the substrate.
In both cases, the light entry or light exit surface of the second optoelectronic component runs parallel to the substrate, and the beam-splitting layer is constructed on a surface that is aligned above this second optoelectronic component at an angle of approximately 45xc2x0 to the substrate.
Since the light entry or light exit surfaces of the optoelectronic components run perpendicular or parallel to the substrate, it is possible to arrange conventional transmitters and/or receivers directly on the substrate without additional special support elements. As a result, the planar design is simplified and the optoelectronic components can be bonded via very short wires to electric terminals arranged on the substrate. It is possible to achieve high transmission rates because of these short connections.xe2x80x94The optoelectronic components can also be integrated in layer sequences grown on a substrate.
The beam-splitting layer, i.e., the layer acting in a beam splitting fashion that is aligned at an angle of 45xc2x0 to the substrate, splits the light bundle impinging perpendicularly in the direction of the substrate into a first light bundle, running parallel to the substrate, and a second light bundle, running perpendicular to the substrate.
In the reverse direction, the first and the second light bundles are united to form a light bundle running perpendicularly away from the substrate. It is thereby possible to construct the optical coupling device either as a bidirectional transceiving module or as a unidirectional transceiving module. In this way, the optoelectronic components used as receivers can have a small light entry surface because of the perpendicular incidence of light.
With regard to the use of optoelectronic components that transmit or receive beams of different wavelengths, it is advantageous when the layer acting in a beam splitting fashion is constructed as a wavelength-selective reflecting layer.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an optical coupling configuration, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.